Changing Component Style

Question

I have a component that I want to render with certain styling based upon the props that it will receive. I'm currently defaulting the prop types, and then creating the styling at render as such:

 getDefaultProps: function(){
 return{
 size: "small",
 shape: "rounded"
 };
},
statics : {
 function getShape(shape){
 if(shape === "rounded"){
 return "59px";
 }else{
 return "2px";
 }
 },
 function getSize(size){
 if(size === "large"){
 return "136px";
 }else if(size==="medium"){
 return "68px";
 }else{
 return "34px";
 }
 }
},
render: function(){
 var borderpx = Avatar.getShape(this.props.shape);
 var imgpx = Avatar.getSize(this.props.size);
 return(
 <img src={this.props.img} style={{"border-radius" : borderpx, height: imgpx}} />
 );
}

What I'm trying to figure out:

1. Is this the correct way to "dynamically" render the style in React?
2. Is there anything in my code that I could do better?